ESTRO 2025 - Abstract Book

S713

Clinical - CNS

ESTRO 2025

2995

Digital Poster Overall survival of patients with ten or more brain metastases treated with SRS. Izabela Zarębska 1 , Maciej Blok 1,2 , Adrianna Kaczmarek 1 , Izabela Miechowicz 3 , Maciej Harat 1,2

1 Department of Neurooncology and Radiosurgery, Franciszek Lukaszczyk Oncology Center, Bydgoszcz, Poland. 2 Department of Clinical Medicine, Faculty of Medicine, University of Science and Technology, Bydgoszcz, Poland. 3 Department of Computer Science and Statistics, Poznan University of Medical Sciences, Poznan, Poland Purpose/Objective: Stereotactic radiosurgery (SRS) has demonstrated efficacy in patients with a limited number of brain metastases (BM), but its role in treating ten or more lesions remains unclear. This study evaluates overall survival (OS) in patients with extensive BM treated with SRS, addressing a critical gap in data for this population. Material/Methods: We retrospectively analyzed survival outcomes of 100 patients with ten or more BM treated with dynamic conformal arc (DCA) SRS at a single institution between 2020 and 2023. All patients had a minimum follow-up of 12 months. Results were compared with 117 patients treated for up to ten BM. Patients were grouped by BM count (less than 3, 4–10, 11–20, more than 20 BM), and all met uniform eligibility criteria, including a Zubrod score of ≤2, active systemic treatment, or stable extracranial disease. Results: The longest observed OS in patients with extensive BM was 51.4 months . OS rates at 3, 6, and 12 months after SRS were 64%, 33%, and 12%, respectively. The median OS for patients with more than 20 BM was 5 months. Number of BMs was not related with OS. Comparing median OS across BM subgroups, no significant differences were observed (p=0.68). Conclusion: The study highlights that the survival outcomes in patients with extensive brain metastases treated with SRS using the DCA technique are not only comparable to those with fewer metastases but also emphasize the feasibility of SRS in high-metastatic burden as alternative to WBRT with potential to improve local control and quality of life. The lack of significant differences in survival across subgroups suggests that the number of metastases should not be the sole determinant in excluding patients from SRS. Instead, treatment decisions should consider performance status, systemic disease control, and access to advanced radiotherapy techniques. These findings support a paradigm shift toward more personalized care in managing extensive BM, leveraging advanced radiotherapy techniques to tailor treatment to patient-specific factors rather than relying on outdated numerical thresholds.

Keywords: brain metastases, SRS, overall survival

3001

Poster Discussion Advanced MRI Perfusion Biomarkers for Predicting Relapse Sites in Grade 4 IDH-Mutant Astrocytoma and Glioblastoma Camilla Satragno 1,2,3 , Mohammed El Aichi 1,2 , Killian Sambourg 1,2 , Leo Dautun 1,2 , Alexander Carre 1,2 , Cristina Veres 1,2 , Vjona Cifliku 1,2 , Jade Briend-Diop 1,2 , Cedric Yuste 1,2 , Linda Mrissa 1,2 , Sophie Bockel 1,2 , Noura Sellami 1,2 , Taha Hachemi 4 , Liliana Belgioia 5,6 , Maria Vakalopoulou 7 , Milovan Savanovic 4 , Philippe Maingon 4 , Catherine Jenny 4 , Julian Jacob 4 , Frederic Dhermain 1,2 , Eric Deutsch 1,2 , Charlotte Robert 1,2 1 U1030, ImmunoRadAI, Inserm, Université Paris-Saclay, Institut Gustave Roussy, Villejuif, France. 2 Department of Radiation Oncology, Gustave Roussy, Villejuif, France. 3 Department of experimental medicine, University of Genoa,